           (not (empty? invalid-keys))
           (simple-report-validation-error form (format "Invalid keys (%s) in formula's options map. Valid keys are: :num-trials" (join ", " invalid-keys)))
           
-          (and (:num-trials opt-map) 
-               (not (pos? (:num-trials opt-map))))
-          (simple-report-validation-error form (str ":num-trials must be an integer 1 or greater. You tried to set it to: " (:num-trials opt-map)))
+          (and (:num-trials opts-map) 
+               (not (pos? (:num-trials opts-map))))
+          (simple-report-validation-error form (str ":num-trials must be an integer 1 or greater. You tried to set it to: " (:num-trials opts-map)))
       
           :else 
-          [docstring? opt-map bindings body])))+          [docstring? opts-map bindings body])))
  how many facts are generated per formula."
  {:arglists '([docstring? opts-map? bindings & body])}
  [& args]
  (valid-let [[docstring? opts bindings body] (validate &form)
              fact (formula-fact docstring? body)
              conclusion-signal `(midje.sweet/fact
                                   :always-pass midje.sweet/=> :always-pass 
                                   :formula :formula-conclude )]

    `(try
       (loop [cnt-down# (or (:num-trials ~opts) midje.ideas.formulas/*num-trials*)]
         (when (pos? cnt-down#)
           (let [snd-bindings# ~(vec (take-nth 2 (rest bindings)))
                 ~(vec (take-nth 2 bindings)) snd-bindings#]
             (if ~fact
               (recur (dec cnt-down#))
               (shrink-failure-case ~docstring? 
                                    ~(vec (take-nth 2 bindings)) 
                                    snd-bindings# 
                                    ~body)))))
       (finally
         ~conclusion-signal))))

    form))

(defmethod validate "formula" [[_formula_ & args :as form]]
  (let [[docstring? opts-map bindings body] (deconstruct-formula-args args)
        invalid-keys (remove (partial = :num-trials) (keys opts-map))]
    (cond (not (leaves-contain-arrow? (check-part-of args)))
          (simple-report-validation-error form "There is no expection in your formula form:")
    
